Electric lamp



A. Y. DODGE June 5, 1934.

ELECTRIC LAMP Filed Dec. 5, 1927 PatentedJune 5, 1934 PATENT OFFICEELECTRIC LAMP Adiel Y. Dodge, South Bend, Ind. Application December 5,1927, Serial No. 237,624

9 Claims.

My invention relates to electric lamps.

One of the objects of my invention is to improve the light distributionof elastic lamps of the type comprising a transparent bulb, and afilament housed in said bulb.

A further object of my invention is to improve the light distribution ofelectric bulbs used in connection with concave reflectors as inheadlight construction.

Further objects will appear from the description and claims.

In the drawing, in which seve al embodiments of my invention are shown,

Figure 1 is an axial section through a parabolic reflector showing thebulb in position;

Fig. 2'is an enlarged view of the bulb shown in Fig. 1; 1

Fig. 3 isan enlarged detail view of a small reflector shield in thebulb;

Fig. 4 is an axial section through a reflector showing a different formof bulb;

Fig. 5 is an enlarged view of the bulb shown in Fig. 4;

Fig. 6 is an axial section through a reflector showing still anotherform of bulb;

Fig. 7 is an enlarged view of the bulb shown in Fig. 6; and

Fig. 8 is a section on the line 8-8 of Fig. 7.

Referring to the drawing in detail, and first to Figs. 1, 2 and 3, theconstruction shown therein comprises a parabolic reflector 1, and anelectric lamp 2 mounted therein with the light center 3 substantially ator near the focus of the parabola so that light rays A from the sourcefalling on the reflector are reflected therefrom in substantiallyparallel rays B to give a concentrated beam. The lamp base 4 itself maybe of any usual or suitable construction and its connection with thesocket portion 5 of the reflector may be of any usual or suitableconstruction. In certain installations, such as headlightsforautomobiles, the axis of the bulb may be horizontal and in suchinstallations there is usually a large proportion of the light from thefilament which escapes forwardly through the open front of the reflectorwhich serves very little useful purpose and which, in fact, is oftenharmful in that it causes a disagreeable and dangerous glare.

In my improved bulb means are providedto utilize a large proportion oflight which would otherwise be wasted and also to minimize the glare.The construction provided for this purpose comprises a concave reflectorshield fi'within the bulb 7 mounted on the glass post 8 from which thefilament 9 extends, this mounting being effected by means of a pair ofslender supports 10 secured to opposite sides of the small reflectormember. This reflector member is provided on its inner side with areflecting surface, and this inher reflecting surface is substantiallyspherical,

the center of the spherical surface being substantially at the center ofthe light source 3 so that rays C from this light source are reflectedback substantially toward and through this light source so that theyfall upon the main reflector at an angle which causes them to bereflected forwardly as substantially parallel rays. I also find itadvantageous to provide a small circular opening 11 in the middle of thelarge auxiliary reflector 6 which permits some direct rays D to escapeforwardly therethrough and fall upon a lens construction 12 which may,be formed integral with the glass enclosing bulb 7. I also flnd itadvantageous to cut away the sides of the large auxiliary reflector 6,as shown at 13, to permit a certain amount of forwardly and laterallydirected rays to escape directly to illuminate the side of the roadway.

In Figs. 1 and 2 the light filament is shown revolved 90 out of placefor the sake of ilh stration. Particularly in a two filament bulb, it iscustomary to have the filaments lie in horizontal planes.

The constructions shown in Figs. 4 and 5 comprise a concave reflector 1which may be similar to that described in connection with Fig. 1, and alamp bulb 2 having a connection with the reflector similar to thatdescribed in Fig. 1. In this form no reflector member is provided insidethe lamp bulb 7 but the forward end of the bulb is provided with arelatively large convex lens formation 14 of suincient extent tointercept substantially all of the light from the light source whichdoes not fall upon the parabolic reflector 1. This lens condenses theconical beam which falls thereon from the light source and causes therays E to converge so that the beam finally emerges as a relativelyconcentrated and forwardly directed beam.

The construction shown in Figs. 6, 7, and 8, and the connection betweenthe lamp bulb and reflector may be substantially as disclosed in theforms previously described. The glass filament enclosing bulb 7 isprovided at its forward end with a lens formation 15 of sufficientextent to intercept substantially all of the light rays from the lightsource which do not fall on the main parabolic reflector 1. This lensacts in a manner similar to the lens 14 described in connection withFigs. 4 and 5 to condense the light beam falling thereon. In this form Iprovide a small auxiliary reflector 16 within the bulb which may bemounted directly on the glass post 8 which carries the filament. Thisauxiliary reflector is concave, having a substantially spherical innerreflecting surface, the center of which is substantially in the centerof the light source 3 so that rays F falling thereon are reflected backtoward and through the light source, most of them falling on thecondensing lens 15 to reinforce the beam emitted through this lens. Ifdesired, this condensing lens may be cut away on both sides as indicatedat 17, to permitsome of the rays to escape without substantial change ofdirection forwardly and laterally for illuminating road sides, etc.

The lens 12 shown in Figs. 1 and 2 may be omitted, if desired, since thespread beam emitted through the small hole 12 will not be wide. It isobvious that a bulb can be made embodying both the reflectdrs shown inFigs. 2 and 7. In such a construction the rear mirror would be sodesigned that the greater part of the light reflected therefrom wouldclear-the front mirror.

A double filament bulb may have special advantages in connection withthe constructions disclosed and in Figs. 4 and 5 I have shown twofilaments 18, one above the other, one of which may be used as a drivinglight when no one is approaching and the other of which may be used toavoid glare when a driver is approaching from the opposite direction.

While I have described but one embodiment of my invention, it is obviousthat many modifications therein may occur to those skilled in the art,and I desire, therefore, that my invention be limited only by the scopeof the appended claims and by the prior art.

I claim:

1. An electric lamp comprising a transparent bulb, a filament housed insaid bulb, a base for said lamp at the rear end of the bulb, and areflector in said bulb in front of the filament, said reflector being ofcircular formation with a portion cut away at the side to permit directforward and side illumination.

2. An electric lamp comprising a transparent bulb and a filament housedin said bulb, a base for said lamp at the rear end of the bulb, saidfilament having substantially a point light source and asphericahreflector in said bulb in front of said light source andbetween the light source and the front portion of the bulb and havingsaid light source as its center for directing the rays falling thereonback toward and past the light source to increase the rearwardlydirected illumination, said reflector being cut away at the side from apoint below the level of the light source to a point above the level ofthe light source to permit some direct forward and upward illumination.

3. An electric lamp for automobile headlamps comprising a transparentbulb and a filament housed in said bulb, a base for said lamp at therear end of the bulb, said filament having substantially a point lightsource and a spherical reflecting shield in said bulb locatedclose tothe filament in front of said light source only and between the lightsource and the front portion of the bulb and having said light source asits center for directing the rays falling thereon back toward and pastthe light source to increase the rearwardly directed illumination, meansfor supporting said shield from said base while leaving the space behindand at the sides of said filament substantially unobstructed, so thatlaterally and rearwardly directed rays as well as rays reflected fromsaid shield may pass freely out of said bulb, said shield having alight-emitting aperture at its center portion to enable direct centralforward illumination to reduce the shadow cast by said reflector.

4. An electric lamp comprising a transparent bulb and a filament housedin said bulb, a base for said lamp at the rear end of the bulb, saidfilament having substantially a point light source and a sphericalreflector in said bulb in front of said light source and between thelight source and the front portion of the bulb and having said lightsource as its center for directing the rays falling thereon back'towardand past the light source to increase the rearwardly directedillumination, the path of said rays so directed back being substantiallyunobstructed except for said base, said bulb having a glasspostextending from the base on which the filament is mounted andsupporting stems mounted on the glass post and extending forwardly ofthe point light source for supporting the spherical reflector.

5. An electric lamp comprising a transparent bulb, a filament housed insaid bulb, a base for said lamp at the rear end of the bulb, and ashield in said bulb in front of the filament, said shield being ofcircular formation with a portion cut away at the side to permit directforward and side illumination and having a small aperture at its center.

6. An electric lamp comprising a transparent bulb and a filament housedin said bulb, a base for said lamp at the rear end of the bulb, saidfilament having substantially a point light source and a circularreflector shield in said bulb in front of said light source and betweenthe light source and the front portion of the bulb and having said lightsource as its center for directing the rays falling thereon back towardand past the light source to increase the rearwardly directedillumination, said shield being cut away at the side from a point belowthe level of the light sourceto a point above the level of the lightsource to permit some direct forward and upward illumination.

7. An electric lamp comprising a transparent bulb and a filament housedin said bulb, a base for said lamp at the rear end of the bulb, saidfilament having substantially a point light source, and a sphericalreflecting shield in said bulb located closely in front of said lightsource, said light source being substantially at the center of saidshield, said shield having a small lightemitting aperture at its centerportion to emit direct center forward illumination to partly overcomethe shadow cast by the shield, said bulb being arranged to permitunobstructed passage of rays around the sides of said shield.

8. In an automobile headlamp bulb, a small spherical reflecting segmentset close to the filament blocking the forwardly ascending rays andreflecting them back through the light source and also the central partof the forwardly descending rays, said spherical segment being cut awayat the sides to pass a portion of said forwardly descending rays to theright and to the left forwardly and substantially downwardly toilluminate the edge of the road at close proximity to an automobile inwhich the bulb may be.

9. An electric bulb for an automobile headlamp having a glass bulb, abase and a light filament, and a substantially circular shield locateddirectly in front of said light filament to block forwardly emittingrays in proximity close to the axis of bulb, said shield having its edgecut away at one side below the center line for the emission of forwardand side illumination, and having a small aperture in its centerlessening the shadow cast by the shield.

. ADIEL Y. DODGE.

